ON THE PRONYMPH STAGE IN THE MIGRATORY LOCUST (LOCUSTA MIGRATORIA, ORTHOPTERA, ACRIDIDAE)

ON THE PRONYMPH STAGE IN THE MIGRATORY LOCUST (LOCUSTA MIGRATORIA, ORTHOPTERA, ACRIDIDAE) S. Yu. Chaika Faculty of Biology, Lomonosov Moscow State University, Moscow 119992, Russia e-mail: biochaika1@rambler.ru The structure of the integument, somatic and visceral muscles, midgut, and Malpighian tubules were investigated at the late stages of the embryonic and early postembryonic development of the migratory locust, Locusta migratoria, to assess the organization of its pronymph stage. A vermiform locust larva sometimes called pronymph represents (in relation to its morphogenetic features) the first nymphal instar covered with the second embryonic cuticle, which was not dropped. Since the first instar locust nymph significantly differs in many morphological characters before and after dropping this embryonic cuticle, two successive living forms are suggested to be distinguished. The first form from the moment of developing the third embryonic cuticle to dropping the second one; the second form from dropping of the second embryonic cuticle to the formation of the second nymphal instar cuticle. Due to the fact that the stage of pronymph should precede the nymph stage, the locusts have it fully embryonized and covered with the second embryonic cuticle; it is typical for other insects with hemimetabolous development (Konopova, Zrzavy, 2005). Therefore, to call the first vermiform instar nymph as pronymph is erroneous, since they are separated by the molting process and formation of a new cuticle.